Ys. Ee et al., Effect of transforming growth factor-beta 1 on oestrogen metabolism in MCF-7 and MDA-MB-231 breast cancer cell lines, ONCOL REP, 6(4), 1999, pp. 843-846
Transforming growth factor-beta (TGF-beta) has been shown to inhibit the gr
owth of mammary epithelial cells and map play a protective role in mammary
carcinogenesis. In contrast, oestrogens promote the development of breast c
ancer. Oestrone sulphate (E1S) is a huge reservoir of active oestrogens in
the breast being converted to the weak oestrogen, oestrone (E-1), by oestro
ne sulphatase. E-1 is reversibly converted by oestradiol-17 beta hydroxyste
roid dehydrogenase to the potent oestrogen, oestradiol (E-2). The aim of th
is study was to assess the effect of the TGF-beta 1 isoform on growth and o
estrogen metabolism in the hormone-dependent MCF-7 and hormone-independent
MDA-MB-231 human breast cancer cell lines. The results showed that TGF-beta
1 significantly inhibited cell growth and stimulated the conversion of E1S
to E-1 and E-1 to E-2 in the MCF-7 cell line. In the MDA-MB-231 cell line
TGF-beta 1 significantly stimulated cell growth and inhibited the interconv
ersions between E-1 and E-2. In conclusion, the growth inhibitory effect of
TGF-beta 1 on the MCF-7 cell line would appear to confer a protective effe
ct in breast cancer. However, its ability to increase the amount of E-2 wou
ld increase the risk of breast cancer. Which of these effects predominates
in vivo remains to be explored. The growth stimulatory effect of TGF-beta 1
on the MDA-MB-231 cell line probably acts through a mechanism independent
of the effect of TGF-beta 1 on oestrogen concentrations since this cell lin
e is hormone unresponsive.